The present invention relates to a method of immobilizing plutonium by atomic scale fixation in a crystalline ceramic in order to provide a durable, disposable waste form or product.
With the end of the cold war, it is now necessary to be able to dispose of large quantities of highly pure plutonium, especially plutonium recovered from nuclear weapons. Such plutonium is here referred to as weapons plutonium, indicating that it is not mixed with other nuclides. Heretofore known or proposed methods for the disposal of plutonium are not suitable for disposal of these large quantities of plutonium. In addition, plutonium is highly fissile, and it is necessary to develop extremely durable waste forms which reduce the possibility of mobilization and concentration of plutonium in quantities that can lead to criticality. The known borosilicate glass waste form is not very durable, attains saturation damage due to exposure to radiation in an unacceptably short period of time, and is readily altered, both by physical degradation and chemical alteration under conditions at which waste forms should be stable.
It is therefore an object of the present invention to provide a method that provides for the long-term disposal of plutonium in a waste form for which long-term durability can be confirmed and that overcomes the drawbacks of the heretofore known methods, with the inventive method providing a waste product or form that not only protects the environment but also ensures that the plutonium is not readily recoverable for use in weapons.
This object, and other objects and advantages of the present invention, will appear more clearly from the following specification and examples.